swayfmt: fix indentation after where in fn (#5468)

[sudhackar]

Description

This is a small fix to match the indentation for opening brace after a where clause is seen. This should fix #5468

cc: @Braqzen

The change is near trivial.

Checklist

• [x] I have linked to any relevant issues.
• [x] I have commented my code, particularly in hard-to-understand areas.
• [ ] I have updated the documentation where relevant (API docs, the reference, and the Sway book).
• [x] I have added tests that prove my fix is effective or that my feature works.
• [ ] I have added (or requested a maintainer to add) the necessary Breaking* or New Feature labels where relevant.
• [x] I have done my best to ensure that my PR adheres to the Fuel Labs Code Review Standards.
• [x] I have requested a review from the relevant team or maintainers.

[sudhackar]

failing sway-lsp tests look flaky on local too